Wow, I am late seeing this thread. I say go for the 03.5 conversion, I may be biased but I think it looks hot. As someone said earlier do the conversion first, then buy the other stuff. It's easy to get in over your head real quick.
Oh, by the way: The conversion kit on PG is for the MP3/03 MSP style. For the 03.5 style, you would need to change the spoiler and rear lip (maybe Ken can swap out the 03 parts for those) and you would also need to buy the front lip, plus the grills for it. That's another 250 or more. The MSP bumper reinforcement is like $400 list, but I got the P5 reinforcement for $200 when I did the conversion and works fine.
I'd say circle the for sale section here frequently, you can probably find some of the parts you need for cheap.
Oh, by the way: The conversion kit on PG is for the MP3/03 MSP style. For the 03.5 style, you would need to change the spoiler and rear lip (maybe Ken can swap out the 03 parts for those) and you would also need to buy the front lip, plus the grills for it. That's another 250 or more. The MSP bumper reinforcement is like $400 list, but I got the P5 reinforcement for $200 when I did the conversion and works fine.
I'd say circle the for sale section here frequently, you can probably find some of the parts you need for cheap.